Hybrid Electrochemical Method and System for Syngas Production

Abstract

A syngas generation system includes a molten carbonate fuel cell (MCFC) including a MCFC cathode configured to receive a MCFC cathode input stream including a flue gas stream and a MCFC anode configured to output a MCFC anode exhaust stream including carbon dioxide and steam. The syngas generation system further includes a solid oxide electrolysis cell (SOEC) including an SOEC cathode and an SOEC anode. The SOEC is configured to receive, at the SOEC cathode, an SOEC cathode input stream, the SOEC cathode input stream including at least a portion of the MCFC anode exhaust stream, co-electrolyze carbon dioxide and steam in the SOEC cathode input stream, and output, from the SOEC cathode, an SOEC cathode exhaust stream including carbon monoxide and hydrogen gas.

What is claimed is: 
     
         1 . A syngas generation system comprising:
 a molten carbonate fuel cell (MCFC) comprising a MCFC cathode configured to receive a MCFC cathode input stream comprising a flue gas stream and a MCFC anode configured to output a MCFC anode exhaust stream comprising carbon dioxide and steam; and   a solid oxide electrolysis cell (SOEC) comprising an SOEC cathode and an SOEC anode, the SOEC configured to:
 receive, at the SOEC cathode, an SOEC cathode input stream, the SOEC cathode input stream comprising at least a portion of the MCFC anode exhaust stream; 
 co-electrolyze carbon dioxide and steam in the SOEC cathode input stream; and 
 output, from the SOEC cathode, an SOEC cathode exhaust stream comprising carbon monoxide and hydrogen gas. 
   
     
     
         2 . The syngas generation system of  claim 1 , further comprising a controller configured to control a flow rate of additional steam into the SOEC cathode input stream based on a predetermined target ratio of carbon monoxide to hydrogen gas in the SOEC cathode exhaust stream. 
     
     
         3 . The syngas generation system of  claim 1 , wherein the SOEC is configured to receive electrical power produced by the MCFC. 
     
     
         4 . The syngas generation system of  claim 1 , further comprising a methanation reactor configured to:
 receive a portion of the MCFC anode exhaust stream;   methanate the portion of the MCFC anode exhaust stream; and   output a methanated exhaust stream to the MCFC anode.   
     
     
         5 . The syngas generation system of  claim 4 , wherein the methanation reactor is further configured to receive and methanate a first portion of the SOEC cathode exhaust stream. 
     
     
         6 . The syngas generation system of  claim 4 , wherein the SOEC cathode input stream further comprises a second portion of the SOEC cathode exhaust stream. 
     
     
         7 . The syngas generation system of  claim 1 , wherein the SOEC anode is configured to output an SOEC anode exhaust stream comprising oxygen gas, the syngas generation system further comprising a gasifier configured to:
 receive at least a first portion of the SOEC anode exhaust stream;   gasify biomass using the SOEC anode exhaust stream; and   output a gasified exhaust stream to the MCFC anode.   
     
     
         8 . The syngas generation system of  claim 7 , wherein the MCFC cathode input stream comprises a portion of the MCFC anode exhaust stream. 
     
     
         9 . The syngas generation system of  claim 7 , wherein the SOEC anode is configured to receive a second portion of the SOEC anode exhaust stream. 
     
     
         10 . The syngas generation system of  claim 1 , wherein the SOEC is configured to receive heat generated by the MCFC. 
     
     
         11 . A method of producing syngas using a molten carbonate fuel cell (MCFC) and a solid oxide electrolysis cell (SOEC), the method comprising:
 supplying a flue gas stream to a MCFC cathode of the MCFC, the MCFC configured to output a MCFC anode exhaust stream comprising carbon dioxide and steam from an MCFC anode; and   supplying an SOEC cathode input stream to an SOEC cathode of the SOEC, the SOEC cathode input stream comprising at least a portion of the MCFC anode exhaust stream, the SOEC configured to co-electrolyze carbon dioxide and steam in the SOEC cathode input stream and to output an SOEC cathode exhaust stream comprising carbon monoxide and hydrogen gas.   
     
     
         12 . The method of  claim 11 , further comprising supplying additional steam to the SOEC cathode input stream, wherein an amount of the additional steam supplied to the SOEC cathode exhaust stream is determined based on a predetermined target ratio of carbon monoxide to hydrogen gas in the SOEC cathode exhaust stream. 
     
     
         13 . The method of  claim 11 , further comprising supplying power generated by the MCFC to the SOEC. 
     
     
         14 . The method of  claim 11 , further comprising methanating a portion of the MCFC anode exhaust stream and supplying methanated exhaust to the MCFC anode. 
     
     
         15 . The method of  claim 14 , further comprising methanating a first portion of the SOEC cathode exhaust stream, the methanated exhaust comprising methanated SOEC cathode exhaust. 
     
     
         16 . The method of  claim 14 , further comprising supplying a second portion of the SOEC cathode exhaust stream to the SOEC cathode input stream. 
     
     
         17 . The method of  claim 11 , further comprising:
 gasifying biomass using at least a first portion of an SOEC anode exhaust stream from an SOEC anode of the SOEC; and   supplying a gasified exhaust stream to the MCFC anode.   
     
     
         18 . The method of  claim 17 , further comprising supplying a portion of the MCFC anode exhaust stream to the MCFC cathode. 
     
     
         19 . A syngas generation system comprising:
 a molten carbonate fuel cell (MCFC) comprising a MCFC cathode and an MCFC anode configured to output a MCFC anode exhaust stream comprising carbon dioxide;   a solid oxide electrolysis cell (SOEC) comprising an SOEC anode and an SOEC cathode configured to output an SOEC cathode exhaust stream comprising hydrogen gas; and   a reverse water-gas shift reactor (RWGSR) configured to receive a RWGSR input stream comprising at least a portion of the MCFC anode exhaust stream and at least a portion of the SOEC cathode exhaust stream, the RWGSR configured to output a RWGSR output stream comprising hydrogen and carbon monoxide.   
     
     
         20 . The syngas generation system of  claim 19 , further comprising a controller configured to control a first flow rate of the at least the portion of the MCFC anode exhaust stream and a second flow rate of the at least the portion of the SOEC cathode exhaust stream into the RWGSR input stream, wherein the controller is configured to control the first flow rate and the second flow rate based on a predetermined target ratio of carbon monoxide to hydrogen gas in the RWGSR output stream.